Expandable Sleeve

ABSTRACT

An expandable sleeve for use in a well, comprises a tubular structure including an external sealing layer comprising a compliant material; an intermediate expandable tubular body made from a plastically deformable material; and an internal spring structure such as a helically wound spring; wherein the external sealing layer is disposed on the outer surface of the tubular body, and the internal spring structure is disposed inside the tubular body and acts so as to exert a radial force on the body when in an expanded state. Such a sleeve can be used to seal off perforations and in well completions using slotted liners or in drilling applications.

TECHNICAL FIELD

This invention relates to an expandable sleeve of the type that aregenerally used for lining oil or gas wells.

BACKGROUND ART

Expandable sleeves have been known for some time in the oil and gasindustry as a technique for lining and stablising wells for theproduction of fluids. In use, the sleeve is introduced into the well ina contracted form and then expanded until it contacts the wall of thewell bore. Expansion can be achieved by a number of means, includinginflation with compressed fluid or cold working with a mandrel orrotating expansion tool. The advantages of expandable sleeves (sometimescalled ‘expandable tubulars’ or just ‘expandables’) are well known. Incased wells, expandables can be used to shut off perforations or closeother holes in the casing. In open hole, expandables can be used tostablilise the well. Expandables have also been used to shut offperforations in steam injection wells as is discussed in US 2003015246A. One approach to sealing off perforations described in this documentis the use of a sealing sleeve comprising a cylindrical steel portionwith rubber-like gasket material bonded on the outer surface of thesteel sleeve. Certain problems are identified with such a construction.Another approach to sealing such perforations that is stated asaddressing these problems is the use of a spirally would metal patch.Upon deployment, the patch unwinds within the wellbore and seals theperforation in the casing wall. Spring tension tends to keep the patchsecurely fixed over the perforation.

Where the expandable consists of a steel tube that is expanded, thesteel undergoes plastic deformation in order to provide the increase indiameter required. However, even though plastic deformation will havetaken place, the steel retains some elasticity and so may relaxfollowing removal of the mandrel or expanding tool after expansion. Thisrelaxation may be sufficient to compromise the seal against theperforations or wellbore.

The present invention aims to mitigate the effect of such relaxation.

DISCLOSURE OF THE INVENTION

A first aspect of the invention comprises an expandable sleeve for usein a well, comprising a tubular structure including:

-   -   an external sealing layer comprising a compliant material;    -   an intermediate expandable tubular body made from a plastically        deformable material; and    -   an internal spring structure;    -   wherein the external sealing layer is disposed on the outer        surface of the tubular body, and the internal spring structure        is disposed inside the tubular body and acts so as to exert a        radial force on the body when in an expanded state.

Preferably, the internal spring structure comprises a healically woundspring. In a particularly preferred construction, the spring comprises ahelically would wire of rectangular section.

The spring can be provided with formations that resist compression, forexample, inter-engaging teeth formed on adjacent edges of the springwindings.

The tubular body is typically formed from solid metal such as steel.

To assist in achieving good expansion ratios for the sleeve, the tubularbody can have a corrugated structure prior to expansion.

The external sealing layer is preferably natural or synthetic rubber.

A second aspect of the invention comprises a method of installing anexpandable sleeve according to the first aspect of the invention in awell, comprising:

-   -   lowering the sleeve in an unexpanded form into the well; and    -   expanding the sleeve such that the external layer engages the        wall of the well.

In one embodiment, the internal spring is installed in the tubular bodyin a compressed state prior to lowering the sleeve into the well.

Another embodiment comprises lowering the tubular body into the well andlowering the spring into the tubular body after it has been lowered intothe well. In this case, the spring can be lowered into the tubular bodyafter the tubular body has been expanded.

By providing the internal spring structure, the tendency of the tubularbody to relax is resisted. Also, the spring can provide mechanicalsupport allowing potentially thinner material to be used.

The invention also comprises a method of completing a well, comprisinginstalling a completion string including at least one sleeve accordingto the invention in the well.

Preferably, the completion string comprises an array of slotted linershaving sleeves dispersed at various locations along the array.

In one embodiment, the sleeves are expanded on installation of thecompletion. In another embodiment, one or more of the sleeves isexpanded after installation to allow production management operations tobe performed in the region between the expanded sleeves.

At least one further sleeve can be installed between adjacent expandedsleeves in the completion string to isolate that region.

Sleeves according to the invention can also be used during drillingoperations to stablise the formation being drilled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a horizontal section through a sleeve according to anembodiment of the invention in a well;

FIG. 2 shows a part vertical section of the sleeve of FIG. 1;

FIG. 3 shows a part exploded view of the sleeve of FIGS. 1 and 2;

FIG. 4 shows a horizontal section through a corrugated sleeve accordingto a further embodiment of the invention;

FIG. 5 shows a sleeve with axial reinforcement;

FIG. 6 shows a wireline conveyed expansion tool for use with sleevesaccording to the invention;

FIG. 7 shows a well completion using expandable sleeves according to anembodiment of the invention;

FIG. 8 shows the use of an expandable sleeve according to an embodimentof the invention to isolate a water producing region of a completion asshown in FIG. 6; and

FIG. 9 shows a well completion with length compensation sections.

MODE(S) FOR CARRYING OUT THE INVENTION

Expandable sleeves in accordance with the invention are particularlyuseful in wells such as oil and gas wells. They can be applied duringthe well construction process to stabilise the formation through whichthe well is drilled, or after completion to repair damage or to seal offperforations that are producing unwanted fluids. Other uses will beapparent.

Referring to FIGS. 1-3, the embodiment of the invention shown comprisesa sleeve constructed in three layers; an outside layer 10, andintermediate layer 12 and an internal layer 14. In FIGS. 1-3, the sleeveis installed in a well that has been completed with a steel casing 16secured in the well by cement 17 to provide zonal isolation and physicalsupport. Communication with the producing formation 19 is viaperforations 18 formed through the casing in the usual manner.

The outside layer 10 comprises a thin layer of a sealing compound suchas natural or synthetic rubber. The exact material will be selectedaccording to the physical and chemical environment to which the sleevewill be selected. The principal function of this layer is to provide aseal between the sleeve and the wall outside. The outside layer 10 ispressed against the borehole wall (either open formation or previouslyinstalled tubular such as a cassing 16) by the other layers of thesleeve.

The intermediate layer 12 is a thin solid layer. It is typically couldbe made of metal such as steel of from 1 to 3 mm thickness (largerthicknesses may be used according to requirements). The intermediatelayer 12 ensures proper uniform compression of the outside rubber layer10 against the external wall of the well or casing 16. The thickness ofthe intermediate layer 12 is a compromise between the need to for it todeform easily during the expansion operation, while still being able tosupport the internal well over-pressure, without being extruded intoholes in the well wall or tubular 16 such as perforation 18 or slots.

The internal layer 14 is a spring device 20 that provides elasticexpansion of the sleeve against the well wall after the expanding tool(not shown) has finished the expansion process. Furthermore, thisstructure resists potential collapse of the intermediate layer 12 whenan external pressure is being applied onto the sleeve system.

As is shown more clearly in FIG. 2, the primary seal is provided by therubber outside layer 10 which is pressed against the perforated tubular16 by the expansion force of the thin intermediate metal layer 12reinforced by the radial force generated by the energizer spring 20.

The energizer spring 20 can be an helical spring made of an wound thickwire of a rectangular section. The rectangular wire section allows asmooth contact between the outer surface 22 of the spring 20 and theintermediate thin metal layer 12.

This spring 20 is used to generate a radial expansion to push the sleeveagainst the well wall.

One method of constructing a spring for this application is to start fora tube of an elastic metal. This tube should be slightly too large toenter in the well (especially if the thicknesses of the rubber outerlayer 10 and thin metal intermediate layer 12 are taken into account).The metal tube is then cut following a spiral line to form the springhelix. To install the spring, it is necessary to reduce its diameter;for this action, an axial force is applied to stretch the hellicoidalstructure (to separate the coils) then a torque is applied to reduce thehelix diameter.

This spring 20 can have a number of functions when installed in the wellin the sleeve. For example, the spring 20 can ensure that theintermediate metal layer 12 is maintained in a cylindrical shape afterits plastic deformation in the expansion process. This can beparticularly useful if the sleeve was initially vertically corrugatedprior to expansion as is shown in FIG. 4.

The spring 20 can also act to reinforce the sealing effect of the outerrubber layer 10 against the well wall (either open-hole well-bore or theperforated casing 16, or the slotted liner, or any other metal tubular).The extra energization may be useful because the intermediate metallayer 12 has been plastically deformed against the well-wall; when themechanical force applied for this deformation (expansion) is removed,the intermediate metal layer 12 will relax slightly due to the elasticproperty of the metal.

The spring 20 will act to support the sleeve when external pressure fromthe formation is applied. On its own, the relatively thin intermediatelayer 12 would have tendency to collapse, as it is thin and typicallynot fully cylindrical after its plastic expansion against the well wall.

When installed in the well, the spring 20 can provide a reserve ofpotential energy, so that the sealing effect of the out rubber layer 10can be maintained and re-adjusted in case of slight movement either ofthe sleeve or the wall. Such movement may occur due to thermal andpressure variation, or due to some slight displacement of the structurerelative to the wall. Such movement can occur in open-hole situations,as the wall itself may move due to change in fluid wetting or subsidenceeffects.

It is particularly preferred that the spring 20 is designed for alocking effect after installation. This effect can be achieved byfriction between the spring 20 and the inner wall of the intermediatelayer 12, or by a ratchet effect created by the structure of the edgesof the coils of the spring 20. For example, the helicoidal cut used tomake the spring can be in the form of a toothed line so that the teethon adjacent parts of the coils interact and lock the spring in place.The locking effect is preferably directional, so that the spring canexpand but retraction is resisted by the interlocking formations.

The spring may be installed in the sleeve in a number of ways. In somecases, the spring may be lowered into the well directly with theintermediate and outer layers as a single unit, with the spring in itscompressed state. Such an approach can apply particularly when thesleeve expansion ratio is limited. However, when large sleeve expansionratios are envisaged (particularly when a corrugated structure is usedto provide a greatly reduced starting diameter), it may be easier toinstall the spring after the intermediate and outer layers have beeninstalled and expanded. In such a case, the expandable structure may beinstalled and expanded in a first run of a setting tool and the springinstalled after expansion by a second run of a setting tool.

The basic sleeve according to one embodiment of the invention includes aintermediate thin layer 12. Typically, this is initially cylindrical.While this layer is usually metal, other materials capable of easyplastic deformation are also possible. This layer will be plasticallydeformed to the final diameter, by a mechanical device which generates aradial expansion. Starting with a cylindrical intermediate layer, theexpansion is limited typically to 20%-30%. Expansion is limited by theintrinsic properties of the material of the intermediate layer. Forlarger expansion ratios, the intermediate metal layer may need to becorrugated prior to installation as is shown in FIG. 4.

The intermediate layer can be optimised for minimizing the forcerequired for expansion. One approach is to use a slightly corrugatedsleeve with corrugations of relatively small depth and relatively butshort in circumferential extent (small wavelength pattern) so that manycorrugations can be formed over the circumference. Such small butnumerous corrugations allows extension of the sleeve under a relativelysmall force. However, the maximum extension may be limited. The use of acorrugated sleeve allows the energizer spring to act more freely toapply the sleeve against the wall. When the corrugations are axial, theymay also provide some support over perforations, so that internalpressure does not extrude the thin intermediate layer into theperforations.

In case of open-hole application, the small numerous corrugation sleevemay be replaced by a small numerous dimples sleeve. With this sleeve,the wavy pattern is available for all direction, so that the sleeve cancomply to more type of deformation of the open-hole surface.

A sleeve according to the invention can be used in the role of anexternal casing packer (ECP) or a liner packer. In this role, the sleeveis installed as a special tubular between either screen sections orslotted liners, during the installation of the completion. The sleeve ishandled and installed as the other elements of the completion. Used insuch an application, the sleeve will typically have certaincharacteristics, including:

-   -   a sleeve diameter similar to that of the screens or slotted        liners;    -   connections provided at both ends of the sleeve, similar to the        screens or liners.    -   axial load and torque strength similar to the screens or slotted        liners; and    -   a length adapted to the particular field needs (typically        recommended to be longer than 3 meters to ensure sufficient        sealing after expansion).

When compared to a conventional ECP, the expandable sleeve according tothe invention is more simple, as the control and setting mechanisms canbe contained in a wireline setting tool. Compared to an ECP, theexpandable sleeve has the advantage of not being susceptible to leaks inthe packer element (which, when they appear in an ECP prohibit propersetting).

The expandable sleeve according to the invention contains its “reserve”of potential energy to adapt its seal when required due to smallmovement of the formation or the device itself. Such adaptation is notpossible with a conventional ECP.

For an ECP-like application, the sleeve is preferably initiallycylindrical and expanded to final diameter by plastic deformation(typically less than 20%). In such a case, the intermediate layerpreferably is able to support the weight of the completion while runningin the hole. However, if this layer has insufficient strength to supportthis axial load, a slotted liner sleeve may be added at the inside theintermediate layer and attached to both end of the expandable sleeve asis shown schematically in FIG. 5. The cuts in the slotted sleeve 23 areparallel to the axis of the tubular so that relatively high axial loadscan be supported, while relatively little effort is required duringradial expansion.

For this application, the spring may have to generate a relatively highradial force to deform the intermediate layer (as it may be relativelythick). Consequently, a thick hericoidal spring may have to be forcedinto place with a high axial load. Extreme axial loads can be achievedby hammering axially onto the spring in-situ.

In an ECP-like application, it is not necessary that the sleeve beexpanded initially. Production may start without expansion. Theexpansion would be performed only when fluid management is required.This situation may be particularly preferable if the length of thesleeve is large compared to the total length of the completion; with thenon-expanded situation, production may be provided in front of thenone-expanded sleeve.

Another application of sleeves according to the invention is in thedomain of through-tubing fluid shut-off. The expansion of metal istypically less than 30% in the plastic domain, but for someapplications, larger expansion may be required. In the case ofperforation shut-off, the sleeve may need to be lowered through theproduction tubing to enter the well, and then expanded to the casing. Inthis application, the required expansion may be up to three-fold. Toachieve this large ratio, a corrugated sleeve such as that shown in FIG.4 may be used. The intermediate layer may need to be relatively thin aslarge bending deformation is required. The rubber outer layer may alsobe of variable thickness in the corrugated shape, so that it has auniform thicknesses after expansion into a cylindrical shape. Typically,it is thinner at the tip of the corrugation, and thicker at the recesspart of the corrugation.

This sleeve may have a retraction effect after setting, trying to moveelastically to its initial shape (usually only by a small percentage ofthe deformation). To avoid this retraction, the inside layer provided,for example, by the energizer spring is required. The length of thesleeve can be selected depending of the length of entry port(perforation, slots) to be sealed.

When installed over slotted liner or screens, the water shut-off sleeveshould extend across a perforated/slotted section and reach the adjacentsections without perforations or slots. Furthermore, these adjacentsections need to seal in the outside annulus.

For these and other applications, once the sleeve has been lowered tothe proper depth in the well, it must be expanded. One way in which thisexpansion can be performed is by use of a wireline expansion tool suchas is shown in FIG. 6. It is common that installation of expandablesleeves may have to take place in a well that is lined with a casing 16and has production tubing 24 secured therein by means of a packer 26.Consequently, the expansion tool 28 will be dimensioned to pass throughproduction tubing. The sleeve 30, preferably in corrugated form, islocated on the expansion tool 28 and the two are positioned together inthe well prior to expansion of the sleeve, after which the tool 28 iswithdrawn.

The expansion tool ensures the cold forming of the sleeve to its finaldiameter, pressing the sleeve against the well wall. Various expandingprocesses can be used:

-   -   Use of a set of rollers that rotates inside the sleeve with a        slow vertical displacement.    -   Use of a cone, which is forced axially inside the sleeve. This        cone has to expand the diameter of the sleeve in order for it to        pass through. The contact between the cone and the sleeve could        be via rollers.

In some applications, it may be necessary to retrieve a sleeve that hasbeen installed within a completion for production management (ortreatment management). For this application, it may be necessary toretrieve the energizing spring must first. Therefore, the spring designmay be adapted to this requirement:

-   -   For example, both ends of the spring may be equipped with easy        to connect termination, so that the wireline tool can connect to        it and apply torque and tensile load to make the overall        diameter of the spring shrink to its original dimension. Then        the spring is maintained in the retracted shape and returned to        surface. The termination could for example be rolled towards the        inside of the bore to approximately 180 deg (and in a small        radius).    -   Another connection technique is to equip both ends of the spring        with small holes to allow a finger on the recovery tool to        connect and apply the retraction load.    -   Another alternative is to push the spring out of the sleeve and        leave it in the well below (or above the sleeve).

Following this, there are several techniques for removal of the sleeve:

-   -   Make a axial cut in the sleeve, so that it can rolled on itself        and removed out of the well.    -   Use a sleeve with an axial weak line. Thanks to the weak-line,        the sleeve can be stripped away from the wall. After being        stripped, the sleeve can be rolled as in the solution proposed        above. The weak line can be provided by the construction of the        sleeve which can be formed by rolling a sheet and welding it as        a cylinder. The weld can be made fragile (especially when the        proper force is being applied). One way to achieve the weak weld        is to use a band which is “glued” or spot-welded on to the        extremities of the intermediate layer to form a joint to create        the tubular form. To break the sleeve, the lower end of the band        is grabbed by the recovery tool, for example by a hook; the        recovery tool can then pull the band away.

Another application of expandable sleeves according to the invention isas replacement for packer (ECP) as is shows schematically in FIG. 7. Theexpandable sleeves 30 are installed as completion tubulars betweenscreens or slotted liners 32, for example in a horizontal section of awell 34. Multiples sleeves 30 can be installed in one completion string(possibly as many as 100 in a long horizontal well). The completion(typically also comprising the slotted liners 32) is installed at thedesired depth. An expansion tool is lowered to the end of thecompletion, and then pulled to the last sleeve (already in place withthe completion) which needs expansion. The expansion tool ensures allthe expansion of all sleeves in one single run in the hole. After theexpansion of all of the sleeves 32, the contact with the reservoir iscompartmented.

Thanks to the compartmentalisation, it is possible to control waterproduction by isolating any sections producing water, for examplesection 36 in FIG. 7, while leaving the remaining sections 38 open toproduce oil. This isolation can be performed by installing anotherexpandable sleeve for internal bore use as is shown schematically inFIG. 8. This sleeve 40 is sized to extend over the distance between twosuccessive completion sleeves 30 to ensure isolation of the waterproducing section 36.

Isolation of the water producing sections can be performed either at thebeginning of the production phase (if the well passes through zonesproducing water and oil) or when the problem starts (for example whenthe oil water contact moves as the reservoir becomes depleted).

In another version of this application, expansion of the sleeves 30 ofthe completion is not performed at the time the completion is installed.In this case the sleeves 30 are expanded only when water entry occurs. Afurther modification of this approach is to only expand the sleeves 30at both ends of the water-producing section 36. This can give moreflexibility for the operation, while ensuring maximum producing contactwith the reservoir.

Another application for the invention can be for length compensationfollowing expansion as is shown in FIG. 9. The expanded sleeve has ashorter length after expansion. As first approximation, the sleevetypically shrinks in length at the same percentage as it has beenexpanded. For example, a 5 meter sleeve expanded by 10% in diametercould shrink in length by 0.5 meter.

When multiple sleeves are installed in the completion, problems mayoccur when the sleeves are not expanded in the successive order. For acompletion equipped with three or more expandable sleeves (see FIG. 9),if sleeves 30 at the extremities are expanded first, the screens (ortubulars) 30 between them are normally in a neutral state. When a sleeve30 in the middle is expanded, shrinkage occurs in length, generating atensile load on the whole tubular completion. To avoid this situation,the intermediate expandable sleeve 30 can be equipped with a“length-compensation” tubular 42. When the intermediate sleeve shrinksits length, this section of compensation tubular extends under low axialload.

The length compensation tubular section 42 can be made ofcircumferentially corrugated pipe (bellows shape). It can also be madeof pipe with a spiral deformation (such as a thread). This shape allowsaxial deformation under load. Such a structure may be limited in axialload capability. For this purpose, the length compensation tubular mayneed axial reinforcement to support the maximum weight of thecompletion. If present, any axial load member providing suchreinforcement needs to be deactivated before starting the expansion ofthe neighbouring expandable sleeve, so that length compensation can beperformed by the compensation sleeve. The deactivation of the axialreinforcement members of the length compensation sleeve can be obtainedat the beginning of the expansion process by cracking links radially,for example by local radial deformation of the reinforcement members.This can be achieved by the radial expansion device used to expand thesleeve. Alternatively, a latch system can be disengaged radially to freethis axial reinforcement system.

During drilling operations, certain formations may be encountered thatcan give rise to problems if left untreated while drilling continues. Insome case, these formation may be mechanically fragile orunconsolidated, or chemically reactive with the drilling fluid, orfractured so as to lead to high fluid loss. An insulating sleeveaccording to the invention can be installed over the problematic zoneand drilling may continue. To avoid loss of well diameter after thesleeve installation, it may be desirable to under-ream the well borebefore the sleeve installation. The sleeve is then lowered with theexpansion tool. The sleeve is expanded over the under-reamed section.

1. An expandable sleeve for use in a well, comprising a tubularstructure including: an external sealing layer comprising a compliantmaterial; an intermediate expandable tubular body made from aplastically deformable material; and an internal spring structure;wherein the external sealing layer is disposed on the outer surface ofthe tubular body, and the internal spring structure is disposed insidethe tubular body and acts so as to exert a radial force on the body whenin an expanded state.
 2. A sleeve as claimed in claim 1, wherein theinternal spring structure comprises a helically wound spring.
 3. Asleeve as claimed in claim 2, wherein the internal spring structurecomprises a helically would wire of rectangular section.
 4. A sleeve asclaimed in claim 2, wherein the internal spring structure is providedwith formations that resist compression.
 5. A sleeve as claimed in claim4, wherein the formations comprise inter-engaging teeth formed onadjacent edges of the spring windings.
 6. A sleeve as claimed in claim1, wherein the tubular body is formed from solid metal.
 7. A sleeve asclaimed in claim 1, wherein the tubular body has a corugated structureprior to expansion.
 8. A sleeve as claimed in claim 1, wherein theexternal sealing layer is natural or synthetic rubber.
 9. A sleeve asclaimed in claim 1, further comprising an axial reinforcement structurefor supporting axial load on the sleeve.
 10. A sleeve as claimed inclaim 9, wherein the axial reinforcement structure is provided by afurther layer located inside the intermediate layer and attached at theextremities of the sleeve.
 11. A method of installing an expandablesleeve as claimed in any preceding claim in a well, comprising: loweringthe sleeve in an unexpanded form into the well; and expanding the sleevesuch that the external layer engages the wall of the well.
 12. A methodas claimed in claim 11, wherein the internal spring is installed in thetubular body in a compressed state prior to lowering the sleeve into thewell.
 13. A method as claimed in claim 11, comprising lowering thetubular body into the well and lowering the spring into the tubular bodyafter it has been lowered into the well.
 14. A method as claimed inclaim 13, comprising lowering the spring into the tubular body after thetubular body has been expanded.
 15. A method of completing a well,comprising installing a completion string including at least one sleeveas claimed in claim 1 in the well.
 16. A method as claimed in claim 15,wherein the completion string comprises an array of slotted linershaving sleeves as claimed in claim 1 dispersed at various locationsalong the array.
 17. A method as claimed in claim 16, wherein thesleeves are expanded on installation of the completion.
 18. A method asclaimed in claim 16, wherein one or more of the sleeves is expandedafter installation to allow production management operations to beperformed in the region between the expanded sleeves.
 19. A method asclaimed in claim 17, further comprising installing at least one furthersleeve as claimed in claim 1 between adjacent expanded sleeves in thecompletion string to isolate that region.
 20. A method as claimed inclaim 16, further comprising associating axially deformable sectionswith at least some of the expandable sleeves so as to compensate forchanges in length of the completion string on expansion of sleeves. 21.A method as claimed in claim 20, wherein the axially deformable sectionscomprise circumferential or helical corrugations.
 22. The use of asleeve as claimed in claim 1 during drilling operations to stabilise theformation being drilled.